Vitamin D Fails in Postmenopausal Osteoporosis Prevention Save
JAMA reports that investigators from the University of Wisconsin in Madison studied the impact of vitamin D supplements on 230 women who were at least five years past menopause but no older than 75, and without osteoporosis at the start of the study. Women were randomly assigned to either placebo or vitamin D - 800 IU daily or 50,000 IU every 15 days - for a year.
Total fractional calcium absorption from the gut increased 1 percent among women on the higher dose of vitamin D, but declined 2 percent with the lower dose and 1.3 percent with the placebo. Similarly, there was no effect on changes in spine, mean total-hip, mean femoral neck, or total-body bone mineral density, trabecular bone score or muscle mass.
The found that low- and high-dose cholecalciferol were equivalent to placebo in their effects on bone and muscle outcomes in this cohort of postmenopausal women with 25(OH)D levels less than 30 ng/mL.
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The one year duration means that there would have to be a huge change in BMD to be noted, as BMD changes are slow and often take two years or more to be seen. I cannot agree that a one year study proves vitamin D is ineffective.
I agree Andy. But recognize this was a short term study and that the primary endpoint was both the influence of vitamin D on intestinal absorption of Calcium (where you would expect a difference) and the DXA changes (where you may not expect a difference).
What about bone turnover markers? These are much more responsive. DXA takes much longer. What happened to the Vitamin D blood levels?
There are many other extra-skeletal effects of vitamin D. Such are muscle effects and potential immunological effects. These patients are vitamin D deficient to begin with. Did they become sufficient at the end of the study?
Oh Dr. Goldman....You always have the right questions, which leaves me with no answers. Bone markers, Vit D levels would have been interesting here. I feel like a fellow during journal club....I didnt do the study...I just chose it because I knew it was interesting and may generate lively discussion!
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